Vacuum-tight joint for electrode lead-ins



May 24, 1938. u. LAMM VACUUM TIGHT JOINT FOR ELECTRODE LEAD-INS FiledFeb. 20, 1936 In yen for Patented May 24,1938

UNITED STATES VACUUM-TIGHT JOINT FOR ELECTRODE LEAD-INS Uno Lamm,Ludvika, Sweden, assignor to Allmi'mna Svenska Elektriska Aktiebolaget,Vasteras, Sweden, a corporation of Sweden Application February 20, 1936,Serial No. 64,893 In Sweden February 27, 1935 3 Claims.

In ionic valves with liquid cathode which in practice must be placed atthe bottom of the valve vessel, it has been found suitable for severalreasons to introduce the conductors leading to all or some of the otherelectrodes, as the main anodes, exciting anodes and igniting anode,through the bottom of the vessel. It will hereby for instance bepossible to assemble all the delicate parts of the apparatus on a singlesupporting member, on which they may readily be inspected at the veryinstant before the closing and subsequent evacuation of the vessel. Thesaid arrangement is also advantageous from an electromagnetic point ofview, for instance by reason 16 of the comparatively smallself-inductance of the circuits.

It can, however, not be avoided that the electrodes introduced throughthe bottom offer somewhat greater difliculties as regards the vacuumtight joints than such electrodes introduced through the top. For thelatter, as is well-known, mercury sealed joints are often employed, thecharacteristic feature of said joints being that a column of mercury isplaced outside a solid packing and serves not only to complete but alsoto check the vacuum tightness, a lack of such a tightness beingimmediately revealed by mercury leaking into the vacuum vessel. Suchjoints are very suitable for electrodes introduced through the top whereoutside is equivalent to above, but

they cannot be simply applied to electrodes introduced to the bottomwhere outside means below. According to the present invention, however,the dimculty is solved in such a way that the inner one of two partsintended to form a tight joint against each other is provided with aflange having an annular groove on its upper side, said groove embracingpartly the outer one of the two said parts so that the spacetherebetween can be filled by a sealing liquid, for instance mercury.

A form of the invention is illustrated in the accompanying drawing,which shows in a vertical section the two vacuum tight joints between ananode conductor, entering through the bottom of a valve vessel, and thesurrounding insulator and between the latter and the surrounding bottomof the vessel.

l is the anode conductor (anode bolt), 2 the insulator bushing and 3 thesurrounding bottom of the vessel. To the lower end of the anode bolt I,there is welded the flange 4, which has on its upper side an annulargroove surrounding the bolt. The innermost portion of this groove ispreferably plane at the bottom, and a tight joint is made between thisplane portion and a correspondingly plane, preferably ground portion ofthe insulator by means of a packing 5. Outside the latter, the spacebetween the flange 4 and the insulator 2 is filled with a suitablesealing liquid, for instance mercury, and outside the lat- 5 ter thereis another packing 6 for preventing a spilling or an evaporation of theliquid.

In order to form a tight joint against the bottom 3 of the vessel, theinsulator 2 is in its turn provided with a flange l, which forms on itsupper 10 side an annular groove, into which a ring 8 welded to thebottom 3 engages. The solid packing 8 between this ring and theinsulator 2, which forms the principal vacuum tight joint, lies in thisform considerably above the lowest portion 15 of the annular groove andalso above the highest portion of the flange 1, but by reason of thevacuum on the inside, the interspace can be kept filled with sealingliquid without the latter having any tendency to flow out over theflange I. The an advantage of placing the said joint surface on a. highlevel is among others that a plane grinding thereof is facilitated. Foradditional safety,

a packing i0 is also here placed outside the sealing liquid.

The drawing also shows a grid conductor introduced through the insulator2. The said conductor consists of a vertical portion I I and a portionl2 inclined upwards and outwards, said two portions being in aconducting connection with each 30 other by at least the lower portionof the former and the inner portion of the latter being surrounded bymercury in the space l3. The outer portion of the inclined conductor isfilled with cement l4, and the sealing is completed by the 35 mercury.

I claim as my invention:-

1. In a joint for an ionic valve, a metal vessel,

8. bolt-shaped anode conductor penetrating through the bottom of saidvessel, an insulator 40 surrounding a part of said conductor, a flangeintegral with the lower portion of said conductor and forming togethertherewith an upwardly open annular groove for embracing acorrespondingly shaped convex portion at the bottom of said insu- 45lator, a packing between said insulator and said flange, and a sealingliquid filling the free space of said annular groove outside saidpacking.

2. In a joint for an ionic valve, :3. metal vessel, an electrodeconductor penetrating through the 50 bottom of said vessel, an insulatorsurrounding a part of said conductor, an upwardly open annular grooveformed in the outer portion of said insulator, an annular ridge on thebase of said vessel engaging said groove, a vacuum-tight joint pro- 55vided between said insulator and said vessel and located above saidgroove and closer to said conductor, and a sealing liquid filling thefree space of said groove.

3. In a joint for an ionic valve, a metal vessel, a bolt-shaped anodeconductor penetrating through the bottom of said vessel, an insulatorsurrounding a part of said conductor, a flange integral with the lowerportion of said conductor and forming together therewith an upwardlyopen annular groove for embracing a correspondingly shaped portion atthe bottom of said insulator, a sealing liquid filling the free space ofsaid annular groove, and a conductor penetrating said insulator andcomprising two portions meeting each other at an acute angle and aquantity of mercury engaging both said portions.

UNO LAMM.

